Collingwood Nick wrote:
You'd think someone as smart as he would have learned to adapt to life a little better.
It is his genius that provides for his cushion from reality.
I'd read/heard some suggestions that identify Sheldon's various neuroses, there are many. Obsessive compulsive disorder and Asperger's syndrome were two common suggestions. It could be also argued that it is in poor taste to use archetypes for comedy that involve mental illnesses. Those with that argument have likely never been exposed to Family Guy or South Park.
Howard is obnoxious, Leonard has low self esteem and Raj can't speak to women without alcohol but these are all relatively tame social impediments compared to Sheldon who, for example, can't handle someone sitting in his chair or adjusting to his 'bathroom schedule.' Many of the A plots used to revolve around Sheldon but now that the characters have paired off with partners Sheldon ends up carrying the B plot in the later seasons.